Substances exist in what 3 states
- Solid
- Liquid
- Gas
3 main characteristics of an element
- Consist of only one kind of atom
- Cannot be broken down into simpler type of matter by either physical or chemical means
- Exist as either Atoms or Molecules
Explain Atomic Number
Position in the Periodic Table
What are found in the nucleus
Protons (+)
Neutrons
What Mass does a Proton & Neutron have
1.67 x 10-27 Kg
What are found in the shells of atom
Electrons (-)
Mass of an Electron
9.11 x 10-31 Kg
What is the simplest Atom
Hydrogen - 1 Proton & 1 Electron
Define an Isotope
When an atom gains a neutron through a neclear process.
i.e Isotopes of Carbon are Carbon-12 & Carbon-14
The process by which an atom loses or gains electrons
ionisation
A neutral atom or molecule must gain electrons to become
A negative ion (or Anion)
A neutral atom or molecule must lose electrons to become
A postive ion (or Cation)
What is a Molecule
A molecule is a structure containing two or more atoms held together by chemical bonds e.g O2
Name the two main types of chemical bonds:
- Covalent Bond
- Ionic Bond
Describe a Covalent bond
Covalent bonds forms between two non-metals by sharing electrons.
Describe a Ionic Bond
Ionic bonds occurs when an atom transfers one or more electrons to another atom. The atom losing electrons forms a positive and is usually a metallic element. The atom gaining electrons forms a negative ion and is usually a non metallic element.
Describe a chemical compound
A chemical compound is a pure substance made up from two or more different elements which have been joined together by a chemical reaction. Atoms will be difficult to separate
Describe a Mixture
A mixture is a combination of at least two substances that are not chemically linked, so they can be separated by physical means. Each substance in a mixture keeps its individual properties.
Name the 3 groups mixtures fall into
- Solutions (e.g Sea water)
- Suspensions (e.g Sand in water)
- Colloids (e.g Clouds, Milk)
Describe Particle Arrangement & Behaviour of a solid
- Strong forces of attraction between particles.
- Particles usually in a regular arrangement.
- Particles are close together and vibrate about fixed positions.
Properties of a Solid
- Has a definite shape and volume.
- Has a fixed surface.
- Usually has a high density.
- Cannot easily be compressed.
- Expands a little on heating.
Describe Particle Arrangement & Behaviour of a liquid
- Weak forces of attraction between particles.
- Random arrangement of particles.
- Particles move about freely but are close together.
Properties of a liquid
- Takes the shape of its container.
- Has a definite volume.
- Has a surface.
- High density.
- Cannot easily be compressed.
- Expands on heating.
Describe Particle Arrangement & Behaviour of a Gas
- Very weak forces of attraction between particles.
- Random arrangement of particles.
- Particles move about freely and are far apart.
